I am trying to make a dynamic filtering mechanism with c#.
I have user class with properties like Name, Surname, BirthDate etc. and Also UserInformations list which is a list of a UserInformation object. UserInformation object has attributes Id, Name and Value. And userList from a list of users.
I created a UI to create filter page using https://querybuilder.js.org/demo.html
It generates filter like
{
"condition": "AND",
"rules": [
{
"id": "name",
"field": "name",
"type": "string",
"input": "text",
"operator": "equal",
"value": "huseyin"
},
{
"condition": "OR",
"rules": [
{
"id": "surname",
"field": "surname",
"type": "string",
"input": "text",
"operator": "equal",
"value": "34"
},
{
"id": "ix_2_Weight",
"field": "ix_2_Weight",
"type": "integer",
"input": "select",
"operator": "equal",
"value": 50
}
]
}
],
"valid": true
}
I have no problem with filters with attributes of User. However, I am trying to filter informations in UserInformations Array. I am splitting field name if its start with ix and get id of the user information. But i could not find how to compare its value. if it were a static linq, it shoud have been like
users.Where(u=>u.Informations.FirstOrDefault(i=>i.id==2/*id of information in filter*/)?.Value=="something"))
Filter is called with below code
private async Task<List<User>> FilterUsers(FilterRule rule, List<UserFilterDto> users = null)
{
List<User> list = users ?? await GetUsersForFilter();
var tempList = list.BuildQuery(rule).ToList();
return tempList;
}
And Dynamic query part is as below.
public static IQueryable<User> BuildQuery(this IQueryable<User> queryable, FilterRule filterRule, out string parsedQuery, bool useIndexedProperty = false, string indexedPropertyName = null)
{
if (filterRule == null)
{
parsedQuery = "";
return queryable;
}
var pe = Expression.Parameter(typeof(UserDetailedDto), "item");
var expressionTree = BuildExpressionTree(pe, filterRule, useIndexedProperty, indexedPropertyName);
if (expressionTree == null)
{
parsedQuery = "";
return queryable;
}
parsedQuery = expressionTree.ToString();
var whereCallExpression = Expression.Call(
typeof(Queryable),
"Where",
new[] { queryable.ElementType },
queryable.Expression,
Expression.Lambda<Func<UserDetailedDto, bool>>(expressionTree, pe));
var filteredResults = queryable.Provider.CreateQuery<UserDetailedDto>(whereCallExpression);
return filteredResults;
}
public static IQueryable<User> BuildQuery(this IQueryable<User> queryable, FilterRule filterRule, out string parsedQuery, bool useIndexedProperty = false, string indexedPropertyName = null)
{
if (filterRule == null)
{
parsedQuery = "";
return queryable;
}
var pe = Expression.Parameter(typeof(UserDetailedDto), "item");
var expressionTree = BuildExpressionTree(pe, filterRule, useIndexedProperty, indexedPropertyName);
if (expressionTree == null)
{
parsedQuery = "";
return queryable;
}
parsedQuery = expressionTree.ToString();
var whereCallExpression = Expression.Call(
typeof(Queryable),
"Where",
new[] { queryable.ElementType },
queryable.Expression,
Expression.Lambda<Func<UserDetailedDto, bool>>(expressionTree, pe));
var filteredResults = queryable.Provider.CreateQuery<UserDetailedDto>(whereCallExpression);
return filteredResults;
}
private static Expression BuildExpressionTree(ParameterExpression pe, FilterRule rule, bool useIndexedProperty = false, string indexedPropertyName = null)
{
if (rule.Rules != null && rule.Rules.Any())
{
var expressions =
rule.Rules.Select(childRule => BuildExpressionTree(pe, childRule, useIndexedProperty, indexedPropertyName))
.Where(expression => expression != null)
.ToList();
var expressionTree = expressions.First();
var counter = 1;
while (counter < expressions.Count)
{
expressionTree = rule.Condition.ToLower() == "or"
? Expression.Or(expressionTree, expressions[counter])
: Expression.And(expressionTree, expressions[counter]);
counter++;
}
return expressionTree;
}
if (rule.Field != null)
{
Type type;
switch (rule.Type)
{
case "integer":
type = typeof(int);
break;
case "long":
type = typeof(long);
break;
case "double":
type = typeof(double);
break;
case "string":
type = typeof(string);
break;
case "date":
case "datetime":
type = typeof(DateTime);
break;
case "boolean":
type = typeof(bool);
break;
default:
throw new Exception($"Unexpected data type {rule.Type}");
}
Expression propertyExp = null;
if (rule.Field.StartsWith("ix"))
{
long informationId =long.Parse(rule.Field.Split("_")[1]);
????
????
} else if (useIndexedProperty)
{
propertyExp = Expression.Property(pe, indexedPropertyName, Expression.Constant(rule.Field));
}
else
{
propertyExp = Expression.Property(pe, rule.Field);
}
Expression expression;
if (propertyExp.Type.Name.Contains("ICollection") || propertyExp.Type.Name.Contains("List"))
{
// Rule Field is a Collection
expression = BuildCollectionExpression(pe, rule);
}
else
{
switch (rule.Operator.ToLower())
{
case "in":
expression = In(type, rule.Value, propertyExp);
break;
case "not_in":
expression = NotIn(type, rule.Value, propertyExp);
break;
case "equal":
expression = Equals(type, rule.Value, propertyExp);
break;
case "not_equal":
expression = NotEquals(type, rule.Value, propertyExp);
break;
case "between":
expression = Between(type, rule.Value, propertyExp);
break;
case "not_between":
expression = NotBetween(type, rule.Value, propertyExp);
break;
case "less":
expression = LessThan(type, rule.Value, propertyExp);
break;
case "less_or_equal":
expression = LessThanOrEqual(type, rule.Value, propertyExp);
break;
case "greater":
expression = GreaterThan(type, rule.Value, propertyExp);
break;
case "greater_or_equal":
expression = GreaterThanOrEqual(type, rule.Value, propertyExp);
break;
case "begins_with":
expression = BeginsWith(type, rule.Value, propertyExp);
break;
case "not_begins_with":
expression = NotBeginsWith(type, rule.Value, propertyExp);
break;
case "contains":
expression = Contains(type, rule.Value, propertyExp);
break;
case "not_contains":
expression = NotContains(type, rule.Value, propertyExp);
break;
case "ends_with":
expression = EndsWith(type, rule.Value, propertyExp);
break;
case "not_ends_with":
expression = NotEndsWith(type, rule.Value, propertyExp);
break;
case "is_empty":
expression = IsEmpty(propertyExp);
break;
case "is_not_empty":
expression = IsNotEmpty(propertyExp);
break;
case "is_null":
expression = IsNull(propertyExp);
break;
case "is_not_null":
expression = IsNotNull(propertyExp);
break;
default:
throw new Exception($"Unknown expression operator: {rule.Operator}");
}
}
return expression;
}
return null;
}
